None
the slope of the suggested lines is either 1 or -1
and none of the equal to the slope of the red line in the graph wichc is 2
C(1;2)
a = 1
b = 2
r = 4
(x-a)² + (y-b)² = r²
(x-1)² + (y-2)² = 4²
(x-1)² + (y-2)² = 16
I use it as a short way to say "okay" but I don't know how others may use it.
Your answer would be R=-5x-4+y
